Light barrier

the light barrier is optical/electronic system from sensor (receiver) and source of light (transmitter). The transmitter can consist delivering LEDs of a normal lamp , of infra-red light or of laser light (laser diode). The work principle of a light barrier consists of registering interruptions of the source of shining on the sensorto convert and, usually into shifting processes, which serve for the further processing.

One differentiates between one-way light barriers (transmitters and receivers with respect to separate housings) and reflex light barriers, with which the transmitter and the receiver sit in a housing. The light signal is back thrown over a mirror.

Modern light barriers worknot only on one point but as curtain. So a large surface can be protected, e.g. the interference into a machine can switch the plant off.

If whole surfaces to be supervised are are used a laser scanner. The environment is usually fan-like scanned. Meeting sent light pulseson an object, these are reflected and registered in the receiver of the laser scanner.


  • in the automobile industry
  • packing & foodstuffs industry
  • with electronics production
  • in mechanical engineering
  • in the handling and logistics range
  • smoker identification
  • sport (time measurement)

it become light barriers counting bringing in and driving out passenger car inUnderground parkings and multi-storey car parks uses. In the industry for automation, here for the increased safety of the Bedienpersonales at presses and similar critical devices, for production supervision whether construction units in the correct place of a plate, etc. are positioned.

Web on the left of

operational principle

planning of alarm installation light barriers of thatCompany ABB, pdf (2MB)


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